/*
 * jPOS Project [http://jpos.org]
 * Copyright (C) 2000-2015 Alejandro P. Revilla
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.jpos.iso;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.util.Hashtable;
import java.util.Map;

/**
 * implements a <b>Component</b>
 * within a <b>Composite pattern</b>
 * <p/>
 * See
 * <a href="/doc/javadoc/overview-summary.html">Overview</a> for details.
 *
 * @author apr@cs.com.uy
 * @version $Id$
 * @see ISOMsg
 * @see ISOField
 * @see ISOException
 */
public abstract class ISOComponent implements Cloneable {
	/**
	 * Set a field within this message
	 *
	 * @param c - a component
	 * @throws ISOException
	 */
	public void set(ISOComponent c) throws ISOException {
		throw new ISOException("Can't add to Leaf");
	}

	/**
	 * Unset a field
	 *
	 * @param fldno - the field number
	 * @throws ISOException
	 */
	public void unset(int fldno) throws ISOException {
		throw new ISOException("Can't remove from Leaf");
	}

	/**
	 * In order to interchange <b>Composites</b> and <b>Leafs</b> we use
	 * getComposite(). A <b>Composite component</b> returns itself and
	 * a Leaf returns null. The base class ISOComponent provides
	 * <b>Leaf</b> functionality.
	 *
	 * @return ISOComponent
	 */
	public ISOComponent getComposite() {
		return null;
	}

	/**
	 * valid on Leafs only.
	 * The value returned is used by ISOMsg as a key
	 * to this field.
	 *
	 * @return object representing the field number
	 * @throws ISOException
	 */
	public Object getKey() throws ISOException {
		throw new ISOException("N/A in Composite");
	}

	/**
	 * valid on Leafs only.
	 *
	 * @return object representing the field value
	 * @throws ISOException
	 */
	public Object getValue() throws ISOException {
		throw new ISOException("N/A in Composite");
	}

	/**
	 * get Value as bytes (when possible)
	 *
	 * @return byte[] representing this field
	 * @throws ISOException
	 */
	public byte[] getBytes() throws ISOException {
		throw new ISOException("N/A in Composite");
	}

	/**
	 * a Composite must override this function
	 *
	 * @return the max field number associated with this message
	 */
	public int getMaxField() {
		return 0;
	}

	/**
	 * dummy behaviour - return 0 elements Hashtable
	 *
	 * @return children (in this case 0 children)
	 */
	public Map getChildren() {
		return new Hashtable();
	}

	/**
	 * changes this Component field number<br>
	 * Use with care, this method does not change
	 * any reference held by a Composite.
	 *
	 * @param fieldNumber new field number
	 */
	public abstract void setFieldNumber(int fieldNumber);

	public abstract int getFieldNumber();

	public abstract void setValue(Object obj) throws ISOException;

	public abstract byte[] pack() throws ISOException;

	public abstract int unpack(byte[] b) throws ISOException;

	public abstract void dump(PrintStream p, String indent);

	public void pack(OutputStream out) throws IOException, ISOException {
		out.write(pack());
	}

	public abstract void unpack(InputStream in) throws IOException, ISOException;
}
